There are many options when choosing a corrugated cutterhead for your moulder. Cutterheads can be manufactured in either aluminum or steel, have multiple number of knife configuration, hook angles, and tolerances. The three main types of corrugated cutterheads are; straight bore, hydro-locking, and HSK. There are many considerations that need to be factored in your decision when choosing a corrugated cutterhead for your moulder. Type of material being cut, moulder application, feed rate, price, and concentricity; these are just some of the elements that you must consider when picking a corrugated cutterhead that best fits your needs and budget.
If you are a small shop running material through at 50 feet per minute (FPM) with a single-knife finish then a straight bore cutterhead would meet your needs. A larger operation running material through at 250FPM should be using a hydro-locking cutterhead. Using hydro-locking heads also allows for the use of jointer stones. The jointing process uses an abrasive stone that strikes the knives while the head is rotating. Jointing a cutterhead will make it so that each knife makes the same depth cut as the knife before. If you are consistently running multiple profiles on one machine then a HSK cutterhead would be appropriate. An HSK moulder like the Weinig Powerlock series will cut down on set up times and feasibly increase your productivity. Centric can help you determine what style of corrugated cutterhead will best fit your needs at a price you won’t regret.
Jointing your cutterheads is the process in where all knives in the corrugated cutterhead strike an abrasive stone while in rotation. Jointing ensures that all knives are in the same cutting circle and hitting the cutting surface at equal depths. Jointing will result in a better finish on your product but does dull the cutting edge of the knives. It is important not to over joint in order to safeguard the life of the knives.
A straight bore corrugated moulder head is attached to a spindle by sliding the head on and securing it with a locking nut. The bore on a straight bore cutterhead is normally .001” to .002” oversized to accommodate the fit onto the spindle. Having the cutterhead bore oversized results in a loss of accuracy due to “slop” between the bore and spindle. Slop is reference to the tolerance between the cutterhead and the spindle; a straight bore tolerance is 0.00196” (0.05mm). A tolerance of 0.05mm means that one knife will be higher on the cutting circle than the others; this results in a one knife finish. The most suitable application for a straight bore corrugated cutterhead would be to rough out material before running a final finish on your product. The tolerance of the straight bore makes it difficult to properly joint knifes. Jointing straight bore cutterheads is not recommended. A straight bore cutterhead can be converted into a hydro-lock cutterhead with the addition of an ETP hydro grip sleeve. An ETP hydro grip sleeve fits the bore of the corrugated cutterhead and is pressurized both outward onto the cutterhead and inward onto the spindle. If you are going to joint knifes we would suggest using a modified straight bore with an ETP sleeve, hydro-locking, or HSK corrugated cutterhead.
Integrated hydro-locking heads have self-centering sleeves (SCS) that allows the corrugated cutterhead to be secured directly onto the spindle. Pressurizing the hydro-locking corrugated cutterhead onto the spindle requires a grease gun that can pressurize up to 400psi and 2nd grade lithium grease; such as Centric brand HPG2 lithium grease. Hydro-locking cutterheads create a much tighter fit on both the grinder and moulder. The tolerance of a hydro-locking head is 0.000196” (0.005mm) which makes it excellent for the jointing process. Once pressurized the hydro-locking cutterheads on the moulder need be checked to confirm that no pressure has been lost during operation. If grease pressure is lost then simply add more Centric HPG2 lithium grease to re-pressurize the cutterhead onto the spindle. Keeping your hydro-lock cutterheads pressurized to the correct levels will prevent slop in your spindle/cutterhead tolerance. Slop in the tolerance of a hydro-locking head can result in the cutterhead being spun on the spindle. Spinning a hydro-locking corrugated cutterhead on a spindle is damaging to the spindle. If you do spin the cutterhead on your spindle send the spindle to Centric Inc for a high quality refurbishing that will get your moulder up and running quickly and affordably.
HSK cutterheads are used exclusively with the Weinig Porwerlock series of moulders. Powerlock heads aka HSK cutterheads are the industries best way to switch profiled knives to fit multiple projects. HSK cutterheads are a perfect match for running multiple profiles on one machine. The HSK quick change system allows operators to switch between multiple profiles quickly and easily. HSK cutterheads has doubled the rigidity of the hydro-locking heads and can be run up to 12,000 rpm.